code: def test_tanh_derivative(backend_default):
      inputs = np.array(
          [true_tanh(0), true_tanh(1), true_tanh(-2)]
      ).reshape((3, 1))
      # bprop is on the output
      outputs = np.array(
          [
              1 - true_tanh(0) ** 2,
              1 - true_tanh(1) ** 2,
              1 - true_tanh(-2) ** 2,
          ]
      ).reshape((3, 1))
      compare_tensors(Tanh(), inputs, outputs, deriv=True, tol=1e-7)
  
imports: from math import tanh
  import numpy
  from neon import NervanaObject
  from neon.transforms import Identity, Rectlin, Softmax, Tanh, Logistic, Sign, PixelwiseSoftmax
  from utils import allclose_with_out
label_desc: Use image node_id 22 for calling a global function with example usage: test_tanh_derivative(backend_default) without return types